Find the radius of the circle containing 20 degree arc of a circle whose length is 15 Pi meters

s = rθ where s is the arc length, r is the radius, and theta is the angle (in radians)
We first have to convert 20 degrees tor radians so we do
20 * pi/180 = pi/9
15pi is the s value (arc length) so we have:
15pi = pi/9 * r
15pi / (pi/9) = r
r = 135m